CSS Reset / Normalize *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; } Layout Structure (Flexbox) .container { width: 1200px; margin: 0 auto; } .header { display: flex; justify-content: space-between; align-items: center; } Grid Layout Example .post-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 30px; } Typography Precision Font Loading function basic_theme_fonts() { wp_enqueue_style( 'google-fonts', 'https://fonts.googleapis.com/css2?family=Inter:wght@400;600;700&display=swap', false ); } add_action('wp_enqueue_scripts', 'basic_theme_fonts'); Typography System body { font-family: 'Inter', sans-serif; font-size: 16px; line-height: 1.6; color: #222; } h1 { font-size: 40px; font-weight: 700; } h2 { font-size: 32px; font-weight: 600; } p { margin-bottom: 20px; } header.php <!DOCTYPE html> <html <?php language_attributes(); ?>> <head> <meta charset="<?php bloginfo('charset'); ?>"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <?php wp_head(); ?> </head> <body <?php body_class(); ?>> <header class="site-header"> <div class="container"> <h1 class="logo"> <a href="<?php echo home_url(); ?>"> <?php bloginfo('name'); ?> </a> </h1> <?php wp_nav_menu(array( 'theme_location' => 'primary', 'container' => 'nav', 'menu_class' => 'main-menu' )); ?> </div> </header> Register Menu function basic_theme_setup() { register_nav_menus(array( 'primary' => 'Primary Menu' )); } add_action('after_setup_theme', 'basic_theme_setup'); Responsive Design Viewport Meta <meta name="viewport" content="width=device-width, initial-scale=1.0"> Media Queries @media (max-width: 992px) { .container { width: 90%; } .post-grid { grid-template-columns: 1fr 1fr; } } @media (max-width: 600px) { .post-grid { grid-template-columns: 1fr; } } Custom Single Template <?php get_header(); ?> <main class="single-post container"> <?php if ( have_posts() ) : while ( have_posts() ) : the_post(); ?> <h1><?php the_title(); ?></h1> <?php the_content(); ?> <?php endwhile; endif; ?> </main> <?php get_footer(); ?>